<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
<title></title>
</head>

<body>
<script type="text/javascript">
var email="4006751066@qq.com";
var length=parseInt(email).toString().length;
var QQ=email.substr(0,length);
document.write("邮箱地址：4006751066@qq.com");
document.write("<br>该邮箱地址中的QQ号为"+QQ);
</script>
</body>
</html>
